Conventional archery devices usually include a bow having two arms with a bowstring strung between the ends of the arms. The user grasps the bow and "draws" or pulls back on the bowstring with one hand while pushing the bow itself with the other hand. Drawing the bowstring tends to cause the arms to want move toward each other, creating tension therebetween. The amount of force necessary to draw a given bow is usually measured in pounds and is known as the "draw weight" of the bow. When the bowstring is released, energy is transferred through the bowstring and to the arrow which is propelled or "fired" toward a target.
One method of increasing the speed at which an arrow is propelled is to increase the stiffness of the bow arms. However, the user must be able to draw the bowstring. Thus, increasing the stiffness of the bow arms to create a very high draw weight bow may be useless if the user cannot draw it and hold the bow in the drawn position for a sufficient period of time to aim at the target. If the user is struggling with holding the bow string in the drawn position, his aim will be deleteriously affected.
Crossbow technology was developed to relieve the tension applied to the user's arms as encountered when using a conventional bow as discussed hereinabove. The stock of the crossbow holds the bowstring in the drawn position, allowing the user to aim without concern for manually holding and maintaining the draw weight.
Trigger mechanisms, as known in the art, were developed in order to both hold the bow string in the drawn position, and to release the bowstring when the trigger is operated. Often, a bowstring catch is provided which holds the bowstring until the trigger is manipulated, which in turn rotates or otherwise moves a sear, releasing the bowstring catch and hence, the bowstring itself.
With the development of sophisticated trigger mechanisms, improvements such as safety assemblies were also developed. Safety assemblies are known to include a block plate or the like which may be positively manipulated by the user. Manipulating the block plate in one direction causes the block plate to lock the trigger mechanism, such as by engaging and impeding movement of the sear or another portion of the trigger mechanism which is operatively connected to the bowstring catch. When the user is ready to fire the crossbow, the safety assembly is manipulated in an opposite direction, freeing the movement of the relevant portion of the trigger mechanism. It is also known in the art to provide a safety mechanism which will automatically engage into the "safe" or non-firing position when the bowstring is drawn and placed into engagement with the bowstring catch pin.
In both conventional and crossbow art, it is known that drawing and releasing a bowstring without having an arrow in place and in position to be fired, known as a "dry-fire", can not only cause serious damage to the bow but also potential injury to the user. As previously discussed, bows are intended to transfer energy to the arrow when fired. During a dry-fire, most of the energy remains within the bow arms, and the sudden increase in energy which would normally be transferred to the arrow can damage the bow.
Most knowledgeable archers understand the inherent dangers in dry-firing conventional bows and crossbows. However, it is not uncommon with a crossbow to inadvertently cause a dry-fire. Although this has been known to happen in almost any circumstance, hunters often find that when they are distracted by their quarry, the possibility of a dry-fire increases.
Therefore, a need exists for a device which will prevent a crossbow from being dry-fired, and which will automatically engage into the non-firing position when an arrow is not in place and not in a position to be fired.